vtkQuaternionInterpolator: call the constructor properly
vtkQuaternionInterpolator: call the constructor properly

The old code was calling operator() which returns the value at that
index. This is why initializer lists are better than assignment blocks,
but that's a larger discussion.

Change-Id: I01d20e14494786ce60553789f6027784851a68bc

ashray/VTK-EVM,sumedhasingla/VTK,sankhesh/VTK,jmerkow/VTK,ashray/VTK-EVM,gram526/VTK,ashray/VTK-EVM,keithroe/vtkoptix,demarle/VTK,mspark93/VTK,demarle/VTK,johnkit/vtk-dev,johnkit/vtk-dev,candy7393/VTK,berendkleinhaneveld/VTK,candy7393/VTK,sumedhasingla/VTK,SimVascular/VTK,mspark93/VTK,msmolens/VTK,johnkit/vtk-dev,ashray/VTK-EVM,berendkleinhaneveld/VTK,gram526/VTK,keithroe/vtkoptix,candy7393/VTK,keithroe/vtkoptix,ashray/VTK-EVM,sumedhasingla/VTK,SimVascular/VTK,jmerkow/VTK,msmolens/VTK,hendradarwin/VTK,hendradarwin/VTK,candy7393/VTK,hendradarwin/VTK,sumedhasingla/VTK,msmolens/VTK,ashray/VTK-EVM,gram526/VTK,mspark93/VTK,berendkleinhaneveld/VTK,sumedhasingla/VTK,jmerkow/VTK,sankhesh/VTK,mspark93/VTK,hendradarwin/VTK,msmolens/VTK,mspark93/VTK,demarle/VTK,msmolens/VTK,demarle/VTK,sumedhasingla/VTK,jmerkow/VTK,keithroe/vtkoptix,candy7393/VTK,ashray/VTK-EVM,hendradarwin/VTK,candy7393/VTK,berendkleinhaneveld/VTK,keithroe/vtkoptix,sumedhasingla/VTK,demarle/VTK,msmolens/VTK,jmerkow/VTK,mspark93/VTK,johnkit/vtk-dev,gram526/VTK,jmerkow/VTK,SimVascular/VTK,ashray/VTK-EVM,berendkleinhaneveld/VTK,jmerkow/VTK,gram526/VTK,msmolens/VTK,sankhesh/VTK,jmerkow/VTK,johnkit/vtk-dev,msmolens/VTK,hendradarwin/VTK,sankhesh/VTK,gram526/VTK,SimVascular/VTK,sankhesh/VTK,demarle/VTK,berendkleinhaneveld/VTK,SimVascular/VTK,berendkleinhaneveld/VTK,mspark93/VTK,SimVascular/VTK,gram526/VTK,hendradarwin/VTK,SimVascular/VTK,sankhesh/VTK,candy7393/VTK,sankhesh/VTK,mspark93/VTK,keithroe/vtkoptix,SimVascular/VTK,gram526/VTK,keithroe/vtkoptix,sankhesh/VTK,candy7393/VTK,demarle/VTK,johnkit/vtk-dev,demarle/VTK,sumedhasingla/VTK,johnkit/vtk-dev,keithroe/vtkoptix